A 65-kDa protein from group B Neisseria meningitidis has been purified and characterized. The protein is induced under stationary growth along with another 90-kDa protein. The structure of the 65-kDa stress protein resembles that of Escherichia coli GroEL protein in electron micrographs, but the neisserial protein is not apparently induced by heat shock. A protein which copurifies with the 65-kDa stress protein has been purified and identified as glutamine synthetase. The assembly intermediates of the meningococcal glutamine synthetase are identical with the intermediates of E. coli glutamine synthetase. Denaturation and renaturation of the glutamine synthetase enzyme is being carried out with E. coli GroEL and the meningococcal 65-kDa stress protein. The 90-kDa stress protein has been purified from N. meningitidis and its properties are being studied. The protein seems to be autophosphorylated when incubated with gamma labelled 32P. Tyrosine kinase (src kinase) did not phosphorylate the 90-kDa protein in a kinase reaction. Similarities between this protein and the clp B protein of E. coli is under study. Another 85-kDa meningococcal protein, which copurifies with the 90-kDa protein, cross reacts with antibody against the E. coli clp A protein.